The Liberal Party had come a distant third in 1979, but the by-election came shortly after the formation of the Social Democratic Party (SDP), with whom the Liberals had entered into an electoral pact, the SDP-Liberal Alliance. It was therefore expected that the election would provide a platform for Shirley Williams of the SDP to return to Parliament, having lost her seat in 1979. However, the Liberal Party insisted on their own candidate and selected the lesser known Bill Pitt who had stood in the seat for the previous three general elections and at the time was the London Regional Party Chair.